This invention pertains to the field of focusing particle beams and more particularly, to the focusing of particle beams by means of laser radiation.
An article entitled "Effects of the Gradient of a Strong Electromagnetic Beam on Electrons and Atoms", Soviet Physics JETP, Vol. 15, No. 6, December 1962, pp. 1088-1090, by G. A. Askar'yan discloses the fact that a transverse force is produced on electrons and atoms by a gradient of the intensity of an electromagnetic beam. It also discloses that particles will be pulled into the beam if the frequency of the radiation is below a resonance of the particle, whereas the particles will be forced out of the radiation if the frequency is above the resonance. This effect can be used to create either a rarefaction or a compression of the particle beam at the focus of the radiation.
An article entitled "Observation of Focusing of Neutral Atoms by the Dipole Forces of Resonance-Radiation Pressure", Physical Review Letters, Vol. 41, No. 20, Nov. 13, 1978, pp. 1361-1364 by J. E. Bjorkholm, R. R. Freeman, A. Ashkin and D. B. Pearson demonstrated the above-described effect with a sodium atomic beam and a co-propagating resonant cw laser radiation.